An attachment of the abovementioned type is for example described in Swiss Pat. No. 504 216. In this known construction, the connecting piece consists of two hinge parts which can engage one another, of which hinge parts the one part can be released from its active position of being in engagement with the other part and can be moved into an inactive position in which the boot plate cooperates with the locking mechanism. The one hinge part is thereby fixedly arranged on the boot plate and the other hinge part is releasably arranged on the ski. The hinge part which can be connected to the ski is designed substantially as a tongue or tab which extends in longitudinal direction of the ski and carries on the end adjacent to the tip of the boot two upstanding fins to which a pivot pin is secured and engage open holding eyelets which are provided on the other hinge part. For downhill skiing, the hinge part which is only releasably connected to the ski is removed and the boot plate is received in the usual manner by the ski binding parts which are secured on the ski and which can effect a safety release.
A disadvantage of this known construction consists in the pivot axis which is needed for cross-country skiing lying in front of the tip of the boot and approximately in the upper area of the sole of the boot. This "front connection" leads to early fatigue because the entire weight must be absorbed by the screw which holds the hinge part connected to the boot plate. Finally the hinge part which is releasably connected to the ski must be stored separately during downhill skiing. The hinge part which during downhill skiing extends forwardly and is secured on the sole plate means, in the case of a fall, an additional risk for injury and can itself also be easily damaged.
Also a device is known (Swiss Pat. No. 513 659) in which a sole plate is suited for both cross-country skiing and also downhill skiing. The pivot axis of this known device lies also in front of the tip of the boot and in the upper area of the front holding mechanism so that the earlier mentioned fatigue appearances also occur.
In a different known attachment for the downhill skiing and cross-country skiing according to German OS No. 2 231 058, the ski boot lies, by the interpositioning of a sole plate, between parts of a release ski binding. The boot is held by means of a transverse axle which is defined by a through bolt and extends through a transverse opening in the sole of the boot adjacent the toe thereof. At the rear part of the plate there is provided a swingable snap mechanism which for downhill skiing presses the heel on the plate and releases same for cross-country skiing.
A disadvantage of this device consists in the sole of the boot having an opening therein which serves as a pivot axis and has to be equipped with a separate holding mechanism. Thus common ski boots which are available on the market are not suited for the use of this sole plate. A further disadvantage consists in the holding bolts are required to be guided in or out during every stepping in and out and still an additional lock is required for use thereof. A separate storage of the lock is needed during periods of nonuse. A still further disadvantage consists in a certain play or clearance provided between the opening and the transverse axis for cross-country skiing and this play is disadvantageous for downhill skiing. Since the snap part which holds down the heel does not press the boot on the holding axis, the play or clearance which exists between holding bolt and bore has a disadvantageous effect for the guiding of the ski.
Also devices are known in which the pivot axis is loaded by a spring. U.S. Pat. No. 2,450,526 describes a construction having a pressure spring; U.S. Pat. No. 3,388,918 describes a device for cross-country skiing in which the tension is produced by a resilient safety tensioning means.
German Pat. No. 2 307 427 describes a device for securing a ski boot on the ski in two different positions, namely one position for downhill skiing and one position for cross-country skiing or racing. For this purpose, a support part is utilized between ski boot and ski adjacent the rear area of which the heel holding means can be secured in two different positions. For downhill skiing, the ski boot is held between a front ski binding part which is secured on the ski and the heel holding means and, in this case the heel holding means is fixed on a locking mechanism which is secured to the ski. For cross-country skiing or for racing, the ski boot is moved backwardly on the surface of the support part and is fixed to the support part by a front holding element which, in the downhill skiing position, is swung out of active position and wherein the heel holding means rests in a mounting which is provided on the support parts. To adjust the heel holding means, the support part has at the two sides elongated recesses. Moreover, the support part has a U cross section which permits, on the one hand, an adjustment of the holding part of the heel holding means and, on the other hand, the reception of the locking for said holding part. The support part is supported at its front area on a pivot axis which is held on a ski-fixed fastening part.
This known device permits a support of the ski boot for cross-country skiing and for racing in the toe area, however, it has the following disadvantages. For downhill skiing the ski boot is held in an elevated position by the support part, which position is disadvantageous for guiding the ski. The use of the support part for downhill skiing is not related to the advantages of common sole plates because the ski boot is held between ski-fixed parts--namely the front ski binding part and the heel holding means which is suspended in the ski-fixed locking mechanism. In addition, a ski boot having a soft sole cannot be used because the front area of the ski boot lies free. For downhill skiing there exists a disadvantage in that the heel holding means, which in this case must necessarily be a safety release binding, is hauled along during each step and produces a torque which must be considered and is caused by the arm between the heel holding means and the axis of rotation. This torque stresses the limbs of the skier and can result in premature fatigue. Finally it must also be considered that the heel holding means can also be a type of upright piston bindings so that this device cannot be used in connection with other safety ski bindings.
In conclusion it can therefore be stated that in all efforts which are directed to producing a device which is suited simultaneously for downhill skiing and for cross-country skiing, limitations as to comfort and additional manipulations must be accepted.
The purpose of the invention is to aid and to design an attachment for cross-country skiing of the abovementioned type so that same meets all requirements of cross-country skiing without requiring separate ski binding holding parts for downhill skiing. An as large as possible selection of known ski binding parts is to be used.
The set purpose is inventively attained by the connecting piece being permanently connected to the sole plate, as actually known, by an axle which extends transversely with respect to the longitudinal axis of the ski and is capable of being swung upwardly against the force of a spring, wherein the pivot axis, as is acutally also known, is arranged substantially below the toe area and, in addition, the sole plate which is provided with the connecting piece is capable of being removed for downhill skiing and replaceable, if desired, with a common sole plate.
Through the inventive construction of the attachment, a device is provided for cross-country skiing which combines the advantages of all known devices, permits the use of existing ski boots namely both those with a stiff sole and a soft sole, both in the case of ski binding parts which hold sole plates on the skis and those which permit a direct mounting of ski boots on the skis and can be mounted easily on the skis. For downhill skiing, the attachment is also detached in a simple manner and is replaced if necessary with a common sole plate. If ski binding parts are used which receive the ski boot without using a sole plate, then the release ski binding is ready for downhill skiing after removal of the attachment.